[dependabot:release-train-updater] Review-mode dependency update: bump zizmor-action to v0.6.3

## Dependency Release Train Summary (review mode)

**Target repository (not modified directly):** `github/gh-aw-actions`

### What changed
- Package/ecosystem: GitHub Actions (CI workflow dependency)
- Manifest: `.github/workflows/ci.yml`
- Old: `zizmorcore/zizmor-action@71321a20a9ded102f6e9ce5718a2fcec2c4f70d8` (v0.5.2)
- New: `zizmorcore/zizmor-action@70fb788f84895a7701f5643d103d587e460b5c99` (v0.6.3)
- Update type: minor, action pin bump

### Why now
No open Dependabot/agent PRs exist in the target repo, and it has no `.github/dependabot.yml`, so Actions pins aren't auto-updated. `zizmor-action` v0.5.2 is stale vs. current latest v0.6.3 (bumps default zizmor to 1.30.0).

### Risk
CI-only (lint job), no runtime impact. SHA verified against the `v0.6.3` git tag via GitHub API.

### Validation
- Verified new commit SHA matches `refs/tags/v0.6.3`.
- No target-repo CI execution possible in review mode (no push access).

A full review bundle (patch, summary, validation notes) has been published as a workflow artifact from this run for maintainer review.

**Action:** A maintainer with write access to `github/gh-aw-actions` should apply the one-line SHA/version bump in `.github/workflows/ci.yml` (patch attached in the published artifact) and confirm CI passes.

### Control Plane
- Correlation ID: 33873310314-39
- Central repo: githubnext/gh-aw-cao
- Run URL: https://github.com/githubnext/gh-aw-cao/actions/runs/33873310314

> Generated by [:dependabot: Dependabot / Release Trains](https://github.com/githubnext/gh-aw-cao/actions/runs/33873731839) · copilot · auto · 48 AIC · ⌖ 8.4 AIC · ⊞ 20.5K · [◷](https://github.com/search?q=repo%3Agithubnext%2Fgh-aw-cao+is%3Aissue+%22gh-aw-workflow-call-id%3A+githubnext%2Fgh-aw-cao%2Fdependabot-release-train-updater%22&type=issues)
>

_{Add this agentic workflow to your repo}

To install this agentic workflow, run

```
gh aw add githubnext/gh-aw-cao/.github/workflows/dependabot-release-train-updater.md@main
```

> - [x] expires on Sep 18, 2026, 12:45 PM UTC

The requested change is in github/gh-aw-actions/.github/workflows/ci.yml, not this repository. Start by reviewing the pinned zizmor-action reference and the attached review artifact, then apply the v0.6.3 update with maintainer access and confirm the target repository's CI passes.

Written by the indexing model from the issue text.